Powering system using battery

Thread Starter

bobdxcool

Joined Feb 12, 2012
39
I made an arduino nano IR sensor based auto liquid dispenser. Currently it is being powered by a 12V 2 amps adapter. The 12v adapter is connected to a LM2596 DC to DC buck converter which converts the 12V to 5V and powers the arduino, IR sensor and a regular green LED. Also I am using a RO valve solenoid (rated upto 24V DC) which is being powered by the 12V adapter. So whenever the IR sensor is triggered, the DC motor (5V 200mA) and solenoid (12V 300-500mA) are turned on for 3 seconds.

Now, I intend to power this system via batteries. I am considering the following 3 options.

a.) Lithium batteries in series (4 of 3.7V batteries). But again here I believe things would be complex as I have to make a BMS and charger for this. Is anything available off the shelf so that I can directly integrate the battery and charger with my existing system ?

b.) Connect 8 AAA batteries in series to get 12V. But how long would these batteries last for my application ?

c.) Connect 2 9V batteries in series. Again, can you guys please tell me how long these may last in the system.

Arduino nano I believe consumes 20mA and the IR sensor probably around another 10- 20mA.
If it wasnt for the solenoid, I was considering connecting a mobile power bank to power the system.
 

MisterBill2

Joined Jan 23, 2018
6,383
While you mention battery voltages, the only type actually listed is AA cells, and they will not last so very long because of the standby current. The two power converters consume power constantly, no matter if they are powering a load or not.
So I ask what is the benefit of making the device battery powered? And what are the size constraints? Certainly there are battery assemblies that could run it for a week or a month, but they are neither small nor cheap.
So you will need to know what the constant load current is and what the momentary load current is, and thus determine the number of amp-hours that the device will need each day. Knowing that number the selection of a battey system can procede.
 

Dodgydave

Joined Jun 22, 2012
9,210
3 Lithium 18650 cells in series will give you 12.6V, there are BMS pcbs that are ready made , you need a 13V charger, the length of time for discharge will depend on the battery capacity Ah.
Example if your circuit takes 500mA, then on a 3Ah battery that should be approx 6 Hrs.
 

Thread Starter

bobdxcool

Joined Feb 12, 2012
39
3 Lithium 18650 cells in series will give you 12.6V, there are BMS pcbs that are ready made , you need a 13V charger, the length of time for discharge will depend on the battery capacity Ah.
Example if your circuit takes 500mA, then on a 3Ah battery that should be approx 6 Hrs.
Since AAA wont work, I was thinking of the following 2 solutions:

1.) Use a protection circuit board like one of these (https://aws.robu.in/wp-content/uploads/2017/09/DATASHEET_ROBU.IN_.pdf) and connect 3 18650 batteries (3S1P) with this board. I would able to charge the battery using a dc adapter (13.5 volts) and also simultaneously power the load. Whenever battery is fully charged, I can remove the adpater.

2.) Or use one of these battery packs with BMS (https://robokits.co.in/batteries-ch...1v-2200mah-2c-with-inbuilt-charger-protection). And recharge these batteries at the end of the day for 1.5 hours with a 12V 1 amp adapter.

What do you think ?

Either solution 1 or 2 would give me upto 4 amps of current I believe , which is much more than what I needed.
 

MisterBill2

Joined Jan 23, 2018
6,383
If the system would need to be recharged daily, how much advantage would be provided by including battery power? That is my question. An efficient switching mode power supply of adequate rating should not consume much power, and, in fact, a much lower rated supply plus a "super-capacitor" may handle intermittent use very well.
 

Thread Starter

bobdxcool

Joined Feb 12, 2012
39
If the system would need to be recharged daily, how much advantage would be provided by including battery power? That is my question. An efficient switching mode power supply of adequate rating should not consume much power, and, in fact, a much lower rated supply plus a "super-capacitor" may handle intermittent use very well.
Battery is for places in open spaces without electrical sockets available.
 
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